## Things that can and things that can't be done in PRA (1998)

by
Ulrich Kohlenbach

Citations: | 3 - 1 self |

### BibTeX

@MISC{Kohlenbach98thingsthat,

author = {Ulrich Kohlenbach},

title = {Things that can and things that can't be done in PRA},

year = {1998}

}

### Years of Citing Articles

### OpenURL

### Abstract

It is well-known by now that large parts of (non-constructive) mathematical reasoning can be carried out in systems T which are conservative over primitive recursive arithmetic PRA (and even much weaker systems). On the other hand there are principles S of elementary analysis (like the Bolzano-Weierstra principle, the existence of a limit superior for bounded sequences etc.) which are known to be equivalent to arithmetical comprehension (relative to T ) and therefore go far beyond the strength of PRA (when added to T ). In this paper